Purple

The Tincture Purpure

This discussion relies on Pastoureau's Traité
d'Héraldique.

There has long been some uncertainty about the status of the tincture
purpure in heraldry, for its place is not as firm as that of the others,
and its use is fairly rare. Some authors have even disputed that it is
a true tincture, although the Spanish kingdom of Leon was blazoned:
argent, a lion purpure as early as 1245, and the tincture appears
in French and English armories of the 13th c, and in numerous Round Table
armories of the 14th and 15th c. There is thus no doubt that it was a
color, but there is doubt as to which color it was.

Until the early 15th c., it is usually depicted as a color in-between
grey and brown. Later heraldists have thought that this color was a
result of pigment deterioration; but certain treatises of the 15th c.
make it quite clear that purpure is a combination of the other 4 colors
in equal proportion. It is plausible that, in the 16th c., the diffusion
of Classical culture made most people think of purpure as the Roman
purple, and the color, which was rare in any case, was changed to
purple to accommodate the word, rather than the reverse.

The question is now, where does the name "purpure" itself come from, and
how was it applied to this grey-brown color? It appears that, until 1260-70,
there is a color called "bis", sometimes called "gris" or brun"; the term "bis"
disappears exactly when the term purpure becomes more common, clearly
replacing the former. The key is this: originally, in medieval French
the word "pourpre" or "porpre" was a kind of fabric, and not a color. The
fabric could be tinted in various colors, and (non-heraldic) medieval
texts mention "porpre vermeille", "porpre noire", "porpre verte", etc.
The most common such fabric was a low-quality grade called "porpre bise".
Over time the terms bis and porpre became synonyms, and porpre or purpure
replaced bis.

About 200 arms have been found in Europe using purpure.

The Imperial Purple

Purple (purpura) was the color of the dye extracted from a Mediterranean
shell-fish, of the genus Murex. The city of Tyr in Phoenicia was especially
famous for producing the dye. The color was of many possibile shades
depending on the actual production process, but it was described as
"blood-red". One of its attractions was that it was the only color-fast
dye known to the Ancients: you could wash your toga many times and it would
still be bright red. It was also expensive: the combination of the two made
it a status symbol from very early times, through the Greeks and to the
Romans. By the late Empire, some types of purple were reserved for the
Imperial family and officials. After the conquest of Tyr by Arabs in
the 7th c. the manufacturing continued in the Byzantine Empire, and
they supplied courts and Church with died wool and silk. After the
fall of Byzantium in 1453 the supply disappeared, and in 1464 the Pope
authorized the use of cochineal as an ersatz to die cardinals' and
archbishops' robes. It also seems to be about that time that the
meaning of purple started slipping from crimson-red or blood-red to
our modern mix of red and blue.

The shell-fish Murex still exists, but there are several varieties,
and in spite of Plinus' explanations it is not quite clear how the
dye was made. There have been modern attempts at duplicating the
color, but the pictures I saw were not very convincing, and the
colors ranged from orange to violet.